SuperH (SH) 64-bit RISC Series SH-5 System Architecture, Volume ...

PRELIMINARY DATA
SuperHyway watchpoint comparators 181
Transaction type
The SuperHyway bus may be implemented with multiple segments and separate
request and response segments. At a functional level, the SuperHyway bus analyzer
has no knowledge of multiple bus segments or separate request and response
segments. The debug user sets a single opcode value and an associated opcode mask
in DM.WP_PLX_CTRL and this can be a request opcode or a response opcode depending
on the type of transaction the debug user wants to monitor. This single opcode is
used by the comparators which exist on each request segment and response
segment.
Transaction source
Each SuperHyway request and response carries an 8-bit field that identifies the
originator of the bus request. Each watchpoint has two fields associated with the
source device, one field for the source device value and a second field for a mask. The
mask field allows requests and responses from different devices to be matched.
Destination device
The destination device field in the SuperHyway request and response consists of the
top bits of the address. In the case of SH-5, the destination field is the top 8-bits of
the 32-bit address. Each watchpoint has two fields associated with the destination
device, one field for the destination device value and a second field for a mask. The
mask field allows requests and responses to different devices to be matched.
It is an implementation specific property as to whether the destination comparator
is implemented.
Address
The address field in the request header defines an address in the specified
destination device. In the case of SH-5, this address field is 24-bits wide with the
least-significant 3-bits forced to zero, that is, addresses are always 8-byte aligned.
Watchpoint registers define an address range by means of start address and end
address parameters. The address comparison range can be as small as one bus word
(8-bytes).
D R A FT
SuperHyway responses do not have an address field, so that the watchpoint address
range comparison is ignored for responses.
05-SA-10003 v1.0
SuperH, Inc.
SH-5 System Architecture, Volume 3: Debug